Today's machines, and particularly work vehicles, are becoming increasingly complex in their design thus making it more and more difficult for service personnel to locate defects in machine sensors and systems. In particular, it is sometimes difficult to determine whether a sensor is producing a signal that is truly representative of the actual level of the sensed parameter. This often results in technicians spending time replacing sensors that actually are producing accurate signals which tends to increase the time required, and thus the cost, for repairs.
It is therefore advantageous to determine whether the sensor is producing an accurate signal without replacing the sensor. Since gauges included in the standard operator display do not provide a sufficiently precise readout of the sensed parameter for this purpose, one method of determining the output would be to display the parameter level being reported by the sensor on a digital display and comparing the displayed level to a measurement reported by a test sensor. For example, if the technician is interested in checking the engine coolant temperature sensor, the technician obtains a reference to which to compare the sensor by measuring coolant temperature with a service tool. By comparing the temperatures reported by the vehicle-mounted sensor and the service tool, the technician can determine whether the vehicle-mounted sensor has failed without spending time replacing the sensor.
Since most machines include a number of sensors but only one or two digital displays, a means for selecting one of the parameters to be displayed digitally must be included. Such a means must also include a way to identify the parameter being displayed so the technician is assured that the parameter of interest has been selected.
Prior art systems, such as that disclosed in U.S. Pat. No. 3,906,437 issued to Brandwein et al. on Sep. 16, 1975, have allowed an operator to select one of a plurality of operating parameters to be displayed in a digital format. However, such a system tends to clutter the appearance of the display since the selection means must be permanently affixed to the front of the display and includes, for example, a rotatable switch knob, a plurality of lines extending from the switch knob to the gauges, and a second rotatable switch knob to select parameters not being illustrated by a gauge. While useful if an operator regularly views the digital information while operating the machine, the permanently affixed means for selecting parameters to view digitally and for identifying the selected parameter are generally unnecessary when such information is only desired by service personnel troubleshooting the system.
The present invention is directed at overcoming one or more of the problems as set forth above.